This equipment proposal seeks support for a Philips EM420 electron microscope with EDAX x-ray probe (energy dispersive detector) accessories for use by funded investigators in basic neurosciences in the Department of Anatomy at the University of Rochester School of Medicine. The acquisition of this equipment would benefit many funded projects and would permit the modernization of our EM facility in the face of greatly increased needs in our recently expanded Department. The requested equipment would permit high resolution electron microscopy at a wide range of magnifications, analytical localization and quantitation of chromium-tagged neurotransmitters in ultrastructural compartments, and heavy metal localization and quantitation. Research projects in the areas of central control of blood pressure and hypertension, neural regulation of immune responses, peptide-monoamine interactions, aging changes in peptide and monoamine neurons, neural transplantation, computerized analysis of dendrites in aging brain, quantitative neuroanatomy of cortical damage by methyl mercury, quantitative studies of cells and vessels in dementia, hippocampal alterations in alcohol-preferring rats, and a training program in geriatrics and the neurobiology of aging would benefit from the acquisition of the requested instrumentation.